Progenitor cells are already more specialised than a stem cells and are restricted to differentiate into tissue-specific or organ-specific cells. The most important difference between stem cells and progenitor cells is that progenitor cells have on their surface many regulatory proteins, which provide them with primary specialization. Currently available methods for stem cells separation are inadequate and inefficient as the techniques involved in the isolation of progenitor cells. Certain methods employed for progenitor cells isolation involve destruction of extracellular matrix by collagenase and DNase. Such methodology not only causes the extracellular matrix to be damaged, it also results in the destruction of transmembrane regulatory proteins. Following such procedures, the progenitor cells are no longer intact, no longer possessing proliferative ability and importantly, the vital differentiation capacity is negatively altered.
The extracellular matrix (ECM) is a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells. The ECM is mainly composed of an intricate interlocking mesh of fibrillar and non-fibrillar collagens, elastic fibers and glycosaminoglycan-containing non-collagenous glycoproteins (hyaluronan and proteoglycans). This tissue compartment provides structural support by maintaining organs and complex tissues. ECM of the fetus and the adult is significantly different. In the study by Coolen et al. (2010) most differences between fetal and adult skin were found in the expression pattern of ECM molecules. Both fibronectin and chondroitin sulfate were more abundantly present in the fetal dermis than in adult dermis, and elastin was not found in the fetal skin until 22 weeks of gestation [Coolen N. A., Schouten K., Middelkoop E., Ulrich M. (2010) Arch Dermatol Res].
As has been established by numerous studies, extensive ECM remodeling is critical in many birth-related physiological processes such as cervical ripening, fetal membrane rupture, and placental detachment [Bryant-Greenwood G D, Yamamoto S Y. (1995) Am J Obstet Gynecol; Draper D, McGregor J, Hall J, Jones W, Beutz M, Heine R P, et al. (1995) Am J Obstet Gynecol; Rajabi M R, Dean D D, Beydoun S N, Woessner Jr J F. (1988) Am J Obstet Gynecol; Tsatas D, Baker M S, Rice G E. (1999) J Reprod Fertil; Vadillo-Ortega F, Gonzalez-Avila G, Furth E E, Lei H, Muschel R J, Stetler-Stevenson W G, et al. (1995) Am J Pathol].
Matrix metalloproteinases (MMPs) is a group of zinc-dependent enzymes, play significant roles in such remodeling. Specifically, MMP-2 and MMP-9, known as gelatinase A and B, respectively, are capable of degrading collagen type IV, elastin, and fibronectin and have been identified in the fetal membranes, decidua, and amniotic fluid. Several earlier reports showed that an increase in MMP-9 protein and activity in the fetal membranes, placenta, and amniotic fluid is associated with fetal membrane rupture, term and preterm parturition, and placental detachment from maternal tissue, thus suggesting a role for MMP-9 in these labor-associated events [Hulboy, D. L., Rudolph, L. A., Matrisian, L. M. (1997) Mol Hum Reprod, Tsatas, D., Baker, M. S. and Rice, G. E. (1999) J. Reprod. Fertil; Maymon, E., Romero, R., Pacora, P., Gervasi, M. T., Gomez, R., Edwin, S. S. and Yoon, B. H. (2000) Am. J. Obstet. Gynecol; Yu W H, Woessner Jr J F. (2000) J Biol Chem, Xu, P., Alfaidy, N., Challis, J. R. (2002) J Clin Endocrinol Metab].
MMPs plays a critical role in the invasive growth of the placenta. MMP-2 localized to the amnion mesenchyme, chorion laeve trophoblast, decidua parietalis, and blood vessels in placenta villi. MMP-9 localized mainly to amnion epithelia, chorion laeve trophoblast, decidua parietalis, and placenta syncytiotrophoblasts. Separate cell culture from different layers of fetal membranes and culture of purified placenta trophoblast cells showed that placenta syncytiotrophoblast and amnion epithelial cells exclusively produced MMP-9; chorion trophoblast cells secreted both MMP-2 and MMP-9 [Xu P., Alefaidy N., Challis J. R. G. (2002) J Clin Endocrinol Metal)].
What is needed is a soft natural proteolytic activity of abortive placenta in the present invention to isolate the fetal progenitor cells by minimal manipulation manner.